The thing is, it is supposed to be roughly 45 lines, out to a potential of 80 spaces. I got it to give me the numbers it was using and I got:

0, 5, 11, 16, 22 etc etc etc, up to just shy of 80, where it then turned around and went back towards zero. So it is behaving like a Sine wave should mathematically, but I still am lost as to why it starts to shift at the start, and then sort of dies.

It does not. All it does is increase the numerical output and keep the same style as before. A bump at the start, and then it falls flat.

Also, I do not understand how the Sine could possibly be negative. The function only continues while t < 180. Stopping it at 180 degrees should keep all the numbers positive (or zero, in the case of t=0).